Chicago's oldest zoo animals

Chuck Berman/Chicago Tribune

Aussie, the zoo's 28-year-old male polar bear, begins his day with a swim in his habitat at the Brookfield Zoo. Aussie has arthritis and other issues that come with being an old bear. Male polar bears average life expectancy is around 21 years.

Aussie, the zoo's 28-year-old male polar bear, begins his day with a swim in his habitat at the Brookfield Zoo. Aussie has arthritis and other issues that come with being an old bear. Male polar bears average life expectancy is around 21 years. (Chuck Berman/Chicago Tribune)

Aussie, the zoo's 28-year-old male polar bear, begins his day with a swim in his habitat at the Brookfield Zoo. Aussie has arthritis and other issues that come with being an old bear. Male polar bears average life expectancy is around 21 years.